1. Field of the Invention
This invention relates to an electrode securement sheet for securing an electrode to a living body skin surface in close contact therewith.
2. Prior Art
As is well known in the art, electricity is induced in the living body by the activity of the heart, brain, muscles, etc.
Particularly, electricity produced by the activity of the heart is detected as weak current induced on the surface of the skin of the living body, using an external electrocardiogram to check for abnormality of the heart. To this end, electrodes of an input section of the electrocardiogram are held in close contact with the skin surface of, and thereby electrically coupled to, the living body.
FIGS. 5 to 7 show a prior art electrode that is held in close contact with the skin surface for current derivation. FIG. 5 shows the electrode 7 in perspective. The electrode 7 has a substantially circular sticky sheet piece 8. The sticky sheet piece 8 has a doughnut-like cloth piece having a central opening 9, and its lower surface has enough stickiness to be held in close contact with the skin surface M of the living body as shown in FIG. 7.
An electrode plate engagement member 10 made of a hard synthetic resin is bonded to the upper surface of the sticky sheet piece 8 to close the opening 9. The electrode plate engagement member 10 has a magnetic lead coupler 11 projecting from the upper surface. As shown in FIG. 7, an electrode plate 12, which is held in close contact with the skin surface M of the living body to derive a weak current from the heart, is secured to the lower surface of the lead coupler 11.
FIG. 6 is a back view of a lead connector 13, through which a weak current or voltage derived from the heart through the electrode plate 12 is led via a lead to an electrocardiogram installed in a room. The lead connector 13 has substantially the same size as the electrode 7 and is made of a hard resin. It has a recess 14, and a magnetic electrode coupler 15 is provided in the recess 14 and secured to the lead connector 13. One end of a lead 6 is connected to the electrode coupler 15, and its other end is connected to the electrocardiogram.
To obtain an electrocardiograph using the electrode 7 as described above, the sticky sheet piece 8 of the electrode 7 is first applied to the skin surface M of the living body, as shown in FIG. 7, and then the lead connector 13 is coupled to the electrode 7 by bonding the magnetic electrode coupler 15 of the lead connector 13 to the lead coupler 11 of the electrode 7. In this state, a weak current from the heart, derived through the electrode plate 12, is led through the lead 16 to the electrocardiogram.
Usually, a weak current derived from the skin surface of a patient with a serious cardiac disease in a ward of a hospital through the electrode 7 held in close contact with the skin surface of the patient is led to an electrocardiogram installed in a separate nurse station to be checked by staff members.
However, the lead connector 13 which is coupled to the electrode 17 held in close contact with the patient's skin surface is liable to be shifted from a proper position with respect to the electrode 7 due to an unconscious movement of the patient such as tossing-about in sleep. In such a case, noise is produced, and an accurate electrocardiograph cannot be obtained.
Further, it is possible that the patient would unconsciously pull out the lead 16 of the lead connector 13 from the electrode 7. When the lead connector 13 is detached, an alarm device provided in the nurse station is activated. In this case, the staff members have to hasten to the patient's ward to check the patient's condition.
The alarm device is designed to produce an alarm in an emergency case such as when the pulsation of the heart of a patient is stopped during recording of the patient's electrocardiograph with the electrode 7 held in close contact with the patient's skin surface. With a detachment of the lead connector 13 or electrode 7 from the patient's skin, the alarm device also activated in spite of the fact that the patient's heart, is normal. Even in such a case, the staff members have to hasten from the nurse station to the patient's ward. If the alarm device is frequently erroneously activated, the fatigue of the staff members is increased.
Further, in some cases an electrocardiogram of a patient is recorded while the patient is in motion, depending on the patient's condition. In this case, possible shift or detachment of the lead connector 13 coupled to the electrode held in close contact with the patient's skin surface, which detachment may be caused by a patient's motion, will disable the recording of an accurate electrocardiograph.